readonly [-p] [-a] [-A] [-f] [NAME[=VALUE] ...]
The readonly builtin command is used to mark variables or functions as read-only, which means unchangeable. This implies that it can't be unset anymore. A readonly variable may not be redefined in child scopes. A readonly global may not be redefined as a function local variable. Simple command environment assignments may not reference readonly variables.
| Option | Description |
|---|---|
-a | refer to normal arrays |
-A | refer to associative arrays |
-f | refer to functions |
-p | print all read-only variables or functions, -a, -A and -f can be used to filter. The output is reusable as input |
An argument of -- disables further option processing.
| Status | Reason |
|---|---|
| 0 | no error |
| !=0 | invalid option |
| !=0 | invalid combination of options |
| !=0 | a given NAME is invalid |
-p option is specified